Mars Global Surveyor
Mars Orbiter Camera

A Dust Devil Making a Streak and Climbing a Crater Wall

MGS MOC Release No. MOC2-318, 8 August 2002

Dust devil in E16-01487

Context

One of the key elements of the Mars Global Surveyor (MGS) Mars Orbiter
Camera (MOC) Extended Mission is to look for and monitor changes
taking place on the planet over the course of a second---and,
eventually, a third---martian year. MGS is now well into its second
Mars year, which will draw to a close in December 2002. Among the
changes the MOC has observed are streaks believed to be caused by the
passage of dust devils. Thousands of MOC images show these streaks,
dozens show that they change over time, but far fewer images have
actually captured a dust devil in the act of creating a streak. At
the center right of this image (above left) is a dust devil that, on
May 21, 2002, was seen climbing the wall of a crater at 4.1°S,
9.5°W. This crater (above right) is in western Terra
Meridiani. The dust devil was moving toward the northeast (upper
right), leaving behind a dark trail where a thin coating of surficial
dust was removed or disrupted as the dust devil advanced. Dust devils
most commonly form after noon on days when the martian air is still
(that is, when there isn't even a faint breeze). On such days,
the ground is better able to heat up the air immediately above the
surface. As the warmed near-surface air begins to rise, it also begins
to spin, creating a vortex. The spinning column then moves across the
surface and picks up loose dust (if any is present). The dust makes
the vortex visible and gives it a tornado-like appearance. The dust
devil in this image has a very short, dark shadow cast to the right of
the bright column; this shadow is short because the sun was nearly
overhead.

Images Credit: NASA/JPL/Malin Space Science Systems

Malin Space Science Systems and the California Institute of
Technology built the MOC using spare hardware from the Mars Observer
mission. MSSS operates the camera from its facilities in San Diego,
CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project
operates the Mars Global Surveyor spacecraft with its industrial
partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA
and Denver, CO.